Strong’s Greek
G1479 — ethelothreskeia
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
θρησκεία
ethelothreskeia — pronounced eth-el-oth-race-ki'-ah
from 2309 and 2356; voluntary (arbitrary and unwarranted) piety, i.e. sanctimony:--will worship. see GREEK for 2309 see GREEK for 2356
1 occurrence in the KJV.
Colossians 2:23
Which things have indeed a shew of wisdom in will worship, and humility, and neglecting of the body: not in any honour to the satisfying of the flesh.